Quiet Performance Mufflers/Exhaust

Discussion in 'Technical' started by Phil, May 11, 2016.

  1. 7D2 Grabber

    7D2 Grabber Member

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    When I had a foxbody I used edelbrocks ultra flo's combined with an X pipe and it sounded awesome. Nice and quiet too. If I didn't get a good deal on these used 3" magnaflows I would be looking for the edelbrock mufflers.
     
  2. Phil

    Phil Member

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    All this input is great, I know this response is a little late, but the thought popped into my head again...Stock foxbody mufflers are 15" one side and 17" on the other (to combat drone), and earlier foxbody's are 14" cases. Inside AND outside the car is loud, it's not just an interior resonance problem. I don't mind hacking off the magnaflows and installing stock mufflers if it's going to quiet it down...i have another car that the magnaflows would go on. My setup is in the signature, i'm not really make crazy power (under 300HP to the rear wheels guesstimate).
     
  3. groberts101

    groberts101 Member

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    This " too loud" stuff is highly subjective. Some think low rumbly exhausts are "too loud" while others think "raspy higher pitched" sounding exhausts are too loud. Have a video to share that gives us more perspective?
     
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  4. mojo

    mojo "Everett"- Senior Citizen Supporting Member

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    Agreed, depends on who you ask! Also, depends on what you're using the vehicle for. Long road trips, quiet is most likely the preference; quarter mile or racing -- noise don't enter the equation.
     
  5. groberts101

    groberts101 Member

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    Also consider tailpipe placement since it has a HUGE impact on underbody reverberation. On my last hotrod the extension of the tail pipes by just 1 - 2"(yes.. inches) noticeably changed the tone of the exhaust at idle. Even moreso at higher rev's and especially true while driving with open windows. That TONE change came about by reducing the undercar reverberation affects. The chassis and tunnel/rearend volume is what changes the tone of the exhaust as sound bounces and vibrates the exhaust system underneath the car.

    So again, the overall design and proper suspension(including mount LOCATIONS.. anywhere near the flat floorboard sections is a bad idea if you know anything about how speakers work) of the entire exhaust system, including the improved isolation characteristics that come along with OEM style mounts, is what has the most affect on drone reduction.

    Want some proof? Just for the sake of learning, disconnect ALL mounts(careful not to lower it too much and suspend to much of its weight on the headers and gaskets) and suspend the exhaust system on something padded(very important or the exhaust will still vibrate/resonate to some smaller degree) like heavily folded cardboard or thickly folded insulation. Rags/folded towels work too since it's just a quick and dirty test before pulling the exhaust apart to swap mufflers anyways. This "disconnect" of the exhaust system from the body will eliminate 90% or more of vibrations that cause drone to occur.

    And if you want to go one step further?.. because learning is especially fun when you can actually benefit from it, slide some +1 size tailpipe extensions over the existing tailpipes(if you have chrome tips then you could also insert smaller pipes inside them to avoid scratching your bling). Doesn't have to look pretty and upwards of 1' foot or more can have dramatic impact. Now go sit in the car and rev it. Then have someone else sit in the car and rev it while you stand a short distance away. 3 people is even better when one person connects and disconnects the tailpipe extensions while you compare the differences from inside and out of the cars cabin. Can you hear the before and after differences the added isolation and longer tailpipes add to the equation?

    I've done that same test more than a few times on my own and friends and customers cars. It never ceases to amaze those who have drone issues and often entirely eliminates the need to install new mufflers just to combat it. Also seen a few hard headed guys swap mufflers to only end up with less drone or with it then occurring at slightly different rpm ranges. Basically, the frequency of the mufflers is what affects the drone characteristics of an improperly isolated chassis. Changing mufflers alone only moves the frequency to another which may or may not be less aggravating to your cars chassis and eardrums.. but the existing vibration related drone is still occurring due to improper exhaust system isolation. Fix the underlying issues and you may not need to swap mufflers at all.
     
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  6. Phil

    Phil Member

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    I will try to get a video, but it's hard to show decibel levels via a video. I will say, our old wood windows tend to rattle when the car is idling outside it, if that is any reference to noise level. Groberts, I appreciate the input, I'm trying to get the volume down outside and inside the car, not just when it's being driven, so the whole system needs to be quieted down, which is why I'm trying to find quieter mufflers. I'm sure an exhaust redesign with new mounts would certainly help with interior noise, once the overall volume is cut down, if i need to worry about in-cabin noise, I'll start with smaller modifications. The current tail pipes stick about 1" beyond the rear valence, but I could stick some extensions on there to see if anything changes.

    I suppose my primary question is, what is the maximum length muffler that can fit under a maverick? will 17" work...if so I can put 15, and 17 stock GT mufflers on it, they staggered the sizes to combat drone-apparently it was effective, although like I said, drone isn't really much of an issue here.
     
  7. groberts101

    groberts101 Member

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    Ok, I seemingly ran too far with the drone levels you were describing in the first post. lol

    Point was don't be surprised if the extensions make the exhaust note sound slightly more "distant" and with less sound pressure actually reaching your ears. Probably won't do much for the neighbors windows though. Biggest issue I typically run into is finding that happy medium between looks(better matching rear valance contours) and freely allowing more exhaust pulse strength back under the trunk/rear doghouse to start the process of bouncing around and vibrating these thinner metaled leaf sprung uni-body cars. Allows fewer decibels to make their way around the outlets and back under the rear of the car.. which is basically just a great big drum.. due to the in out pulsing and throbbing exhaust flow. About the best way I could describe it.

    I know what you mean about catching sound in videos but it would still help to gauge what you're considering to be too obnoxious. Otherwise I doubt a 17" case would fit without more extreme tight radius exits to make it over the rearend. My best suggestion is swap in a set of the old standard case dimension Walker dynomax super turbos. I'm pretty sure that the Mustang mufflers flow well for what they are and will surely last much longer than the cheaper super turbos but they would easily be bested in flow potential(reduced pumping losses better overall engine efficiency cleaner tailpipe) by the super turbos. I know from firsthand experience because I and most of my older friends have run dozens of them through the years. Mellow at light to moderate throttle.. powerful sounding when you want to play. They're crimped case designs so you can still pop them open if the carb ever floods the exhaust but they are very good bang for the buck even by today's standards. As with all cheaper turbo mufflers(OEM included).. the sound gets more aggressive over time as soot and oil saturates the packing material.

    Google sound clips of similar combos to yours to get a better idea how they sound. Very mellow sounding at idle for that sleeper effect. Here's a 2010 V8 camaro clip on their site.

    http://www.dynomax.com/sounds-of-dynomax/?muffler=super-turbo-muffler

    Quick question. Does this exhaust currently have a balance pipe or x pipe style crossover? Without one in place each exhaust pipe will have more "pop" from the higher velocity exit speeds. Plenty of better ways to attenuate sound waves than just adding more nooks and crannies from a larger and/or more restrictive muffler design.
     
    Last edited: Apr 1, 2017
  8. Phil

    Phil Member

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    Sorry for the delay! You'll be happy to hear that I did try some extensions on the tailpipes, it sounds a bit quieter on the highway, and I used my decibel app at idle, 78.5 without tips, 77.6 with, so a definitive decrease there!

    My exhaust does have an H-pipe with high-flow cats.

    Actually a lot of noise is now seeming to come from the firewall area, unfortunately it's missing its insulator and some of the larger holes just have tape over them, =/ so that's not helping in that area.

    I'll try to get a picture of the hangers and a video of the exhaust.

    Let me ask you this: I have no hanger forward of the rear of the mufflers, would a properly placed hanger make a difference, and where would you recommend putting it?

    Thank you again for your help!
     
  9. Krazy Comet

    Krazy Comet Tom

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    Well I have these Magnaflow stainless mufflers on the Comet and they SUCK!!! Car has full exhaust system with turndowns at rear valance... Very sharp and raspy tone, will soon be removing them for a pair of Walker Quiet Flows... If that doesn't suit me I'll get some dead stock replacements...

    http://www.jegs.com/p/Magnaflow/Magnaflow-Satin-Stainless-Steel-Mufflers/751042/10002/-1

    Above said I've had Flowmasters on the T-Bird with off road H-pipe since Y2K, are probably as loud but it's a deep and throaty tone... If it's too loud I roll up windows and turn on A/C..

    Cobra Jet has a pair of probably 35+ year old Walker "Red Line Z" Turbo mufflers(long discontinued), love the sound, hopefully the Quiet Flows are similar...
     
  10. Phil

    Phil Member

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    I've heard those are pretty loud, I have the "XL" mufflers, which are supposedly quieter. I love the sound of my exhaust, way better than the flowmaster 40's I have on the my LTD. Let me know how the quiet flows work out, which ones are you buying exactly? (Dimension or car their made for)
     
  11. mojo

    mojo "Everett"- Senior Citizen Supporting Member

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    I have Maremont Universals 158568's -- 17"*13"*2"on my car. I like em. Not loud but nice mellow sound when U step into it.
    I do road trips and like to listen to my music on the road - loud mufflers - not an option. Noise equates to road fatigue much sooner on several hours drive. I bought the car w/ Cherry Bomb straight barrel design, they were almost new; that was the first thing I changed/discarded on the car. They are almost 8 yrs old and still workin fine.
     
  12. Phil

    Phil Member

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    Hmmm, I can't seem to find them online, I think the company may have gone out of business. Lots of items by them being liquidated on random third party sites
     
  13. Krazy Comet

    Krazy Comet Tom

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  14. Krazy Comet

    Krazy Comet Tom

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  15. groberts101

    groberts101 Member

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    wow.. factory stock style mufflers.. you guys really must be older than me! :p

    I always find it funny how alot of gearheads start out pulling factory style mufflers off when we're young and have good ears.. then end up putting them back on when we get older and can hardly hear. Shouldn't the associated hearing losses dictate the need for even louder exhaust systems to get the same overall "hotrod sound effects" as we continue to get older? :D

    Super Turbo's are super quiet IMO and I would never trade any extra flow efficiency for just a few more decibel reductions. But.. I do admit to needing to be yelled at on occasion because my ears don't seem to be gettin' any better either.. so there's that too. :slap: IIRC, but maybe only certain models?.. there were some versions of the walker ST's with 3" internal sized flow tubes. Slowing the exhaust speeds around corners helps reduce flow restriction but also has the secondary side effect of increasing pressure absorption capabilities of the packing through several mechanisms. Slightly slowing hot exhaust flow with subsequent increases in pressure(speed/pressure/gas density relationships) and adding more core area for pressure diffusion is never a bad thing for any chambered and packed muffler design I have ever seen. And I've studied a LOT from all the various manufacturers including most of the smaller aftermarket designs like the spintech's and other boutique designs.

    As for the placement of hangers.. yes mid-point hangers(such as those found in OEM or used to suspend cat's) can help dissipate more energy over a wider area(more small speaker cones vs fewer and larger speaker cones) and also increase muffler hanger lifespan but you need to be VERY careful about placing them too far outside of the tunnel leading into and on ANY of the floorboards, rear incuded. Again with the "great big speaker cone" analogy. The very first time you cut or grind on a completely gutted "economically built" uni-body floor pan(pick a brand).. you will feel and hear what it has to put up when a rumbling and vibrating exhaust system gets pinned up next to it.

    The OEM rubber donut style hangers are excellent as reducing NVH. The extra firewall insulation will surely help more too. Another thing to consider is the extra noise and vibration coming from the headers themselves. Not that you want to go to the extra trouble just for the sake of sound reduction, but aside from slight performance/efficiency gains.. header wraps also help muffle headers to make them less "tinny" sounding.
     

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